Wrist pin retainer



Sept. 18, 1951 G. D. ANGLE 2,568,473

WRIST PIN RETAINER Filed Oct 25, 1946 2 Sheets-Sheet 1 TIL E12.

' INVENTOR GZerzn .ZZAnyZe ATTORNEYS;

p 8, 1951 G. D. ANGLE 2,568,478

WRIST PIN RETAINER Filed Oct. 25, 1946 2 Sheets-Sheet 2 INVENTOR GlennZ7. Arggze ATTORNEY Patented Sept. 18, 1951 WRIST PIN RETAINER Glenn D.Angle, Thomaston, Conn., assignor to The New Britain Machine Company,New

Britain, Conn., a corporation of Connecticut Application October 23,1946, Serial No. 705,187

3 Claims.

. 1 My invention relates to reciprocating engines and in particular toimproved means for retaining in place the wrist pins carried by abig-end or cluster for coupling a plurality of connecting rods to acrankshaft. In radial-type engines the invention is particularlyapplicable to the articulated system employing a so-called solid-ringbig-end, but it will be clear that advantageous results may be obtainedby its application to split and other big-end constructions.

It is an object of my invention to provide an improved means forretaining wrist pins in place in an engine of the character indicated.

It is another object to provide improved means for locking wrist pinsagainst both angular and axial movement, within the space limitationscommon to the above-indicated constructions, and without addingundesirable weight or introducing difficult assembly problems.

It is a further object to provide an improved wrist-pin retainer thatmay be considered foolproof, that is, which will be practicallyimpossible to install incorrectly.

It is, ingeneral, an object of my invention to provide an improvedwrist-pin retainer that will be light in weight, compact, inexpensive tofabricate, efficient, and simple to assemble.

Other objects and various further features of the invention willhereinafter be pointed out or will occur to those skilled in the artfrom a reading of the following specification in conjunction with theaccompanying drawings, in which:

Fig. 1 is a fragmentary vertical sectional view of a five-cylinderradial engine showing a big-end or connecting-rod cluster to which myinvention has been applied;

Fig. 2 is an enlarged fragmentary sectional view taken substantially inthe plane 2-2 of Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view taken substantially inthe plane 3--3 of Fig. 1;

Fig. 4 is an end elevation in partial section of the cluster shown inFig. 1;

Fig. 5 is an elevation of the wrist-pin retainer shown in Fig. 1;

Fig. 6 is a sectional view illustrating a wrist pin according to theinvention, as shown in Fig. 1; and

Fig. '7 is an enlarged fragmentary view illustrating in more detail thefunction of my invention.

Broadly speaking, my invention contemplates wrist-pin-retainer meansengageable with an end of a connecting-rod cluster and so abutting partsof the wrist pins as to retain them against both axial and rotationaldisplacement. In the speciflc form to be described, the retainer issecured to the cluster by means of a bayonet-type engage ment, whereby apartial rotation of the retainer with respect to the cluster may effectlocking engagement against axial displacement. Once so locked, a portionof the retainer may be deformed to lit in a recess within the clusterwhereby rotational dislodgment of the retainer is resisted. The wristpins include longitudinal projections extending beyond the ends of thecluster,

and these projections are eccentrically offset from the axes of thewrist pins. When the retainer is secured in place, these eccentricprojections may abut the retainer to prevent wrist-pin rotation. Sincepart of the retainer radially overlaps portions of the wrist pins, axialdisplacement of the wrist pins is also prevented.

Referring to the drawings, my invention is shown in application to aradial engine It) having five cylinders I l. The pistons l2 within thesecylinders reciprocate to drive a crankshaft [3 about a central axis ofrotation 14. Various 7 means may be employed for connecting the pistonsto the crankshaft, but in the form shown, a so-called solid big-end l5pivotally carries four link-type connecting rods 16 and is lockinglysecured to a master connecting rod 11. Wrist pins l8 passing through thecluster l5 and the ends of the connecting rods l5 and I! serve to tiethe described parts together. The parts which have thus far beendescribed are well known in the art and, therefore, form no part of thepresent invention.

In accordance with the invention, I have provided a novel wrist-pinretainer IQ for securely holding all the wrist pins l8 in place (thatis, against axial displacement) and also for preventing rotation of thewrist pins [8 about their own axes. The retainer ring I9 is engageablewith an end of the cluster 15, and it also abuts each of the wrist pins[8. In the form shown, looking engagement of the retainer 19 with thecluster 15 is of the so-called bayonet-type, that is, radially extendingflanges or projections 20 on the retainer are insertable throughcorresponding recesses 2| .in the cluster l5, and the retainer l9 maythen be partially rotated within an annular groove 22 to efiecta securelocking against axial displacement of the retainer H). To secure theretainer l9 against rotational dislodgment, the retainer l9 may alsoinclude a radially extending tab or other deformable portion 23 whichwill overstand an appropriately shaped recess 24 in the cluster l5 whenthe parts are in their bayonetlocking position. It is clear that slightdeformation of the tab 23, as by tapping with a hammer, will causesecure engagement within the recess 24 so as to prevent dislocation ofthe bayonet look while the engine is in use.

' In the form shown, the groove 22 which accommodates the retainer ring[9 extendsradially inwardly and is defined by the space between the mainbody of the cluster I5 and a radially outwardly extending flange 25.Preferably, the flange extends radially to an extent intermediate theinnermost and outermost extremes of the wrist-pin-receiving bores 26 andof other longitudinally extending apertures :21 (provided in the cluster[5 for purposes of reducing weight) It will be clear that in the processof boring the cluster, arcuate discontinuities (as at 2|) will be formedin the otherwise circumferentially continuous lip of the flange 25.

in accordance'with the invention, the retainer ring I9 is formed on itsinner surface Witha'plura'lityof arcuate lobes or projections 23sosha-ped and placed that the'ring [9 maybe axially insertedpast theflange125-the lobes 26 passing through the arcuate recesses 2|; Uponsubsequent rotation (clockwise, in the sense of Fig. 1) ofthe retainert9 to-effect the bayonet-type'lock ing engagement, it will be clear thatthe lobe '29 will engage'the flange 25 securely against axialdisplacement. When in this locked position the -tab 23 may be tappedinwardly to set in one of the recesses 2c, in order -to give permanencyto the engagement (see Fig. 7). If desired, a saving-inweig-ht may beeffected by piercing the ring 19 with a plurality of apertures 26onepreferably adjacent each of the lobes 2Q.

' "In ac'cqrdancewith a feature of the invention,

' 1 'et a i ner ring I 9 will also have symmetrically disposedlpckinglobes 2d,,so that the retainer l9 may the said to be reversiblyinsertable upon the pluslifir i5-in other words, there would then be,no. wrong way to face the retainer vl9 against the side of theclusterl5v i V It has been indicated that in accordance with the invention thewrist pins l8 are preferably formed with longitudinal extensionsprojecting beyond the end of the main body of the cluster 1,5 o as toengage the outerperiphery of the retainer l9 and thereby to preventrotation of r the wrist pins about their axes. Asshown in Figs. ,6 and7, these projections 36 are preferablyso former; that they will abut theretainer ring [9 with a minimum of angular displacement (with respect tothe axis of the wrist pin I8). In the form shown, the wrist pin I8 isgenerally annular shape with a circular closure disc 2| seated on V ashoulder at each end of the wrist pin. The projections 38 are defined ontheir outer surfaces by continuations of the outer surfaces of wrist pin"lg -andzon their inner surfaces 32 by arcuate lands of substantiallythe same radius as the outer edge of the retainer ring H9. The lands 32are preferably so positioned that-the projections may be said to besubstantially semi-cylindrical.

Thefit resu om this, co s r ion will be understood to permit a minimumof rotational play to the wrist pin and also to provide wear resistancefor a prolonged period. 7

Although I have described the invention as applied to acircumferentially continuous retainer having a bayonet-type lock alongits inner edge, it is clear that the principles of the invention areequally applicable to equivalent forms. For example, the cluster l5could be so formed that the flange 25 defining the locking groove 22faces radially inward, rather than outward as described. In this event,a lobed circumferentially continuous ring the then inwardly facinggroovecould; effectively serve both to lock the wrist'pins l8 againstaxial displacement and against rotational play.

It will'be clear that I have described a simple efficient, and readilyinstallable means for securely "locking wrist pins on a connecting-rodcluster in such a way that minimum wear of all parts will result. Thelocking means requires an absolute minimum of spaceand, with care, itmay be reused in frequent oyerhauls of the enine. V Although I havedescribed my inventionin de tail for the preferred form shown, it willbe understood that modifications may be'made within the scope of theinvention as defined in the'claims which follow.

I claim: r

1. 'In a cluster for coupling a plurality of connecting rods to acrankshaft, a hub including a main body and a radially outwardlyextending flange at each longitudinal end thereof, the outer diameterofsaid flange being less than that of said body whereby radially inwardlyextending retainer-receiving grooves are defined between said body andsaid flanges, said hub including longitudinally extending'wrist-pin-receiving bores through said body and through portions ofsaid flanges whereby circumferentially spaced arcuate recesses areformed in said flanges, and wrist-pin retainers engageable in each ofsaid grooves, each said retainer being circumferentially continuous andgenerally annularwith a predominant inner diameter slightly in excess of.the outer diameter of said flanges and having a pluralityof radiallyinwardly extending arcuate projections circumferentially spaced aboutthe axis of said retainer in accordance with the circumferential spacingof said bores, whereby one of said retainers may be axially insertedover a flange ,to a position substantially coplanar with one of saidgrooves, and further whereby said retainer may be locked between saidflange and said body by a partial rotation thereof, said retainersincluding deformable portions deformable into recesses in said hub tosecure said retainers inlocked position on said hub. y 2; In a clusterfor coupling a plurality of connecting rods to a crankshaft, a hubincluding bayonet-locking means at one end and having a pluralityofwrist-pin-receiving bores open at said end, a wrist pin in one of saidbores and including a longitudinally extendin projection more orless'axially coextensive with said'locking' means, said projection beingeccentric with respect to the axis of said wrist pin, circumferentiallcontinuous wrist-pin-retainer means including a portion for engagementwith said projection whereby said wrist pin may be secured againstrotation about its axis, bayonet-locking means onsaid retainermeans,whereby said wrist pinmay be secured, against axial, displacement fromsaid hub, said retainer means being deformable to lock said retainermeans to said hub.

3. In a cluster for coupling connecting rods to a crankshaft, a hubincluding a radially extending flange defining a radially extendingretainerreceiving groove, said hub having a plurality of longitudinallyextending wrist-pin receiving bores through the body of said hub andthrough parts of said flange, whereby arcuate discontinuities are formedin said flange, the circumferential spacing of said bores to one side ofa plane through an axis of symmetry intersecting the axis of said hubbeing substantially the same as the correspondin bore spacings to theother side of said plane, said hub including a first locking 5 beinserted axially of said flange and rotated so that said projections maybe engaged both by said flange and by the body of said hub, saidretainer including a deformable portion deformable into engagement withone of said abutment means after said ring has been rotated intoengagement with said flange.

GLENN D. ANGLE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 477,941 Jolley June 28, 1892831,602 Cookerley Sept. 25, 1906 1,371,134 West Mar. 8, 1921 1,908,787Pobjoy May 16, 1933 1,911,384 Olson May 30, 1933 1,917,772 Newmann July11, 1933 1,948,475 Newmann Feb. 20, 1934

